Rfid-based sensing of changed condition

ABSTRACT

RFID-based sensors, RFID readers and software sense a changed condition. In one embodiment, an RFID-based sensor includes a base that may be placed at a location where a condition may change. The sensor includes an RFID tag that is coupled to the base. The sensor also includes a detector that can be electrically coupled to the RFID tag. If the condition changes, an electrical property of the detector also changes, impacting an operation of the RFID tag. The impacted operation can be detected by an RFID reader/interrogator so as to provide a notification. An advantage over the prior art is that the condition change can be sensed wirelessly over a domain that can be laborious or hazardous to access otherwise. Moreover, RFID based sensors can be made by modifying common RFID tags.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of co-pending U.S. patentapplication Ser. No. 14/064,515, filed Oct. 28, 2013, which in turnclaims priority from U.S. Provisional Patent Application Ser. No.61/875,600, filed on Sep. 9, 2013, and which further is aContinuation-In-Part of co-pending U.S. patent application Ser. No.13/024,225, filed on Feb. 9, 2011, the disclosure of which is herebyincorporated by reference for all purposes.

This patent application may be found to be related with U.S. patentapplication Ser. No. 14/064,468 filed Oct. 28, 2013 and issued as U.S.Pat. No. 9,237,858 B2.

BACKGROUND

In humans, the heart beats to sustain life. In normal operation, itpumps blood through the various parts of the body. More particularly,the various chambers of the heart contract and expand in a periodic andcoordinated fashion, which causes the blood to be pumped regularly. Morespecifically, the right atrium sends deoxygenated blood into the rightventricle. The right ventricle pumps the blood to the lungs, where itbecomes oxygenated, and from where it returns to the left atrium. Theleft atrium pumps the oxygenated blood to the left ventricle. The leftventricle then expels the blood, forcing it to circulate to the variousparts of the body.

The heart chambers pump because of the heart's electrical controlsystem. More particularly, the sinoatrial (SA) node generates anelectrical impulse, which generates further electrical signals. Thesefurther signals cause the above-described contractions of the variouschambers in the heart, in the correct sequence. The electrical patterncreated by the sinoatrial (SA) node is called a sinus rhythm.

Sometimes, however, the electrical control system of the heartmalfunctions, which can cause the heart to beat irregularly, or not atall. The cardiac rhythm is then generally called an arrhythmia.Arrhythmias may be caused by electrical activity from locations in theheart other than the SA node. Some types of arrhythmia may result ininadequate blood flow, thus reducing the amount of blood pumped to thevarious parts of the body. Some arrhythmias may even result in a SuddenCardiac Arrest (SCA). In a SCA, the heart fails to pump bloodeffectively, and, if not treated, death can occur. In fact, it isestimated that SCA results in more than 250,000 deaths per year in theUnited States alone. Further, a SCA may result from a condition otherthan an arrhythmia.

One type of arrhythmia associated with SCA is known as VentricularFibrillation (VF). VF is a type of malfunction where the ventricles makerapid, uncoordinated movements, instead of the normal contractions. Whenthat happens, the heart does not pump enough blood to deliver enoughoxygen to the vital organs. The person's condition will deterioraterapidly and, if not reversed in time, they will die soon, e.g. withinten minutes.

Ventricular Fibrillation can often be reversed using a life-savingdevice called a defibrillator. A defibrillator, if applied properly, canadminister an electrical shock to the heart. The shock may terminate theVF, thus giving the heart the opportunity to resume pumping blood. If VFis not terminated, the shock may be repeated, often at escalatingenergies.

A challenge with defibrillation is that the electrical shock must beadministered very soon after the onset of VF. There is not much time:the survival rate of persons suffering from VF decreases by about 10%for each minute the administration of a defibrillation shock is delayed.After about 10 minutes, the rate of survival for SCA victims averagesless than 2%.

The challenge of defibrillating early after the onset of VF is being metin a number of ways. First, for some people who are considered to be ata higher risk of VF or other heart arrythmias, an ImplantableCardioverter Defibrillator (ICD) can be implanted surgically. An ICD canmonitor the person's heart, and administer an electrical shock asneeded. As such, an ICD reduces the need to have the higher-risk personbe monitored constantly by medical personnel.

Regardless, VF can occur unpredictably, even to a person who is notconsidered at risk. As such, VF can be experienced by many people wholack the benefit of ICD therapy. When VF occurs to a person who does nothave an ICD, they collapse, because blood flow has stopped. They shouldreceive therapy quickly.

For a VF victim without an ICD, a different type of defibrillator can beused, which is called an external defibrillator. External defibrillatorshave been made portable, so they can be brought to a potential VF victimquickly enough to revive them by a rescuer. For a person at extremelyhigh risk of VF, wearable defibrillators have been made

A problem with defibrillators is that they have electrodes that couldfall off the patient. The electrodes could lose contact with the skin ofthe patient, which prevents them from acquiring an ECG of the patient,and then guiding an electrical shock for defibrillating the patient.

In addition, in the field of sensing, sometimes some locations are noteasily accessible. Radio Frequency Identification (RFID) tags offeradvantages for labeling items and being sensed remotely, but it is oftennot economical to produce small numbers of custom RFID tags for veryspecific purposes.

BRIEF SUMMARY

The present description also gives instances of RFID-based sensors, RFIDreaders and software for sensing a changed condition. Embodiments canalso be applied also to detecting that an electrode does not contactfully a patient's skin.

In one embodiment, an RFID-based sensor includes a base that may beplaced at a location where a condition may change. The sensor includesat least an RFID tag that is coupled to the base. The sensor alsoincludes a detector that can be electrically coupled to the RFID tag. Ifthe condition changes, an electrical property of the detector alsochanges, impacting an operation of the RFID tag. The impacted operationcan be detected by an RFID reader/interrogator so as to provide anotification. An advantage over the prior art is that the conditionchange can be sensed wirelessly over a domain that can be laborious orhazardous to access otherwise. Moreover, RFID based sensors can be madeby modifying common RFID tags.

These and other features and advantages of this description will becomemore readily apparent from the following Detailed Description, whichproceeds with reference to the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a scene where an external defibrillator is usedto save the life of a person according to embodiments.

FIG. 2 is a table listing two main types of the external defibrillatorshown in FIG. 1, and who they might be used by.

FIG. 3 is a diagram showing components of an external defibrillator,such as the one shown in FIG. 1, which is made according to embodiments.

FIG. 4 is a diagram of components of a patient electrode made accordingto embodiments, in a use context.

FIGS. 5A and 5B are diagrams of embodiments of novel use of RFIDtechnology, applied to embodiments of the novel electrodes and systemsof the invention.

FIG. 6 is a diagram of a patient electrode according to an embodimentwhere an output device is coupled to the electrode.

FIG. 7 is a flowchart for illustrating methods according to embodiments.

FIG. 8 is a diagram of a host device that may use an electrode accordingto embodiments.

FIG. 9 is a diagram of components of a wearable defibrillator systemmade according to embodiments.

FIG. 10 is a flowchart for illustrating methods according toembodiments.

FIG. 11 is a diagram illustrating RFID-based wireless sensing of achanged condition, according to embodiments.

FIG. 12 is a diagram illustrating electrical connections for anRFID-based sensor, according to embodiments that can be used to mainlydetune the tag antenna as a result of sensing a changed condition.

FIG. 13 is a diagram illustrating electrical connections for anRFID-based sensor, according to embodiments that can be used mainly todisrupt the tag chip operation as a result of sensing a changedcondition.

FIG. 14 is a flowchart for illustrating methods according toembodiments.

DETAILED DESCRIPTION

As have been mentioned, the present description is about inventions inboth fields of defibrillation and RFID, which have overlap. Embodimentsof the inventions are now described in more detail. This specificationshould be interpreted as a whole, and not as separated by thesubheadings below.

Detecting Loss of Full Skin Contact in Patient Electrodes

FIG. 1 is a diagram of a defibrillation scene. A person 82 is lying ontheir back. Person 82 could be a patient in a hospital, or someone foundunconscious, and then turned to be on their back. Person 82 isexperiencing a condition in their heart 85, which could be VentricularFibrillation (VF).

A portable external defibrillator 100 has been brought close to person82. At least two defibrillation electrodes are usually provided withexternal defibrillator 100, and are sometimes called electrodes. Thefirst electrode is made of a pad 104 and electrode lead 105, and thesecond electrode is made of a pad 108 and electrode lead 109. At leastone of these electrodes has a further component according toembodiments. A rescuer (not shown) has attached pads 104, 108 to theskin of person 82. Defibrillator 100 is administering, via theelectrodes, a brief, strong electric pulse 111 through the body ofperson 82. Pulse 111, also known as a defibrillation shock, goes alsothrough heart 85, in an attempt to restart it, for saving the life ofperson 82.

Defibrillator 100 can be one of different types, each with differentsets of features and capabilities. The set of capabilities ofdefibrillator 100 is determined by planning who would use it, and whattraining they would be likely to have. Examples are now described.

FIG. 2 is a table listing two main types of external defibrillators, andwho they are primarily intended to be used by. A first type ofdefibrillator 100 is generally called a defibrillator-monitor, becauseit is typically formed as a single unit in combination with a patientmonitor. A defibrillator-monitor is sometimes calledmonitor-defibrillator. A defibrillator-monitor is intended to be used bypersons in the medical professions, such as doctors, nurses, paramedics,emergency medical technicians, etc. Such a defibrillator-monitor isintended to be used in a pre-hospital or hospital scenario.

As a defibrillator, the device can be one of different varieties, oreven versatile enough to be able to switch among different modes thatindividually correspond to the varieties. One variety is that of anautomated defibrillator, which can determine whether a shock is neededand, if so, charge to a predetermined energy level and instruct the userto administer the shock. Another variety is that of a manualdefibrillator, where the user determines the need and controlsadministering the shock.

As a patient monitor, the device has features additional to what isminimally needed for mere operation as a defibrillator. These featurescan be for monitoring physiological indicators of a person in anemergency scenario. These physiological indicators are typicallymonitored as signals. For example, these signals can include a person'sfull ECG (electrocardiogram) signals, or impedance between twoelectrodes. Additionally, these signals can be about the person'stemperature, non-invasive blood pressure (NIBP), arterial oxygensaturation/pulse oximetry (SpO2), the concentration or partial pressureof carbon dioxide in the respiratory gases, which is also known ascapnography, and so on. These signals can be further stored and/ortransmitted as patient data.

A second type of external defibrillator 100 is generally called an AED,which stands for “Automated External Defibrillator”. An AED typicallymakes the shock/no shock determination by itself, automatically. Indeed,it can sense enough physiological conditions of the person 82 via onlythe shown defibrillation electrodes 104, 108 of FIG. 1. In its presentembodiments, an AED can either administer the shock automatically, orinstruct the user to do so, e.g. by pushing a button. Being of a muchsimpler construction, an AED typically costs much less than adefibrillator-monitor. As such, it makes sense for a hospital, forexample, to deploy AEDs at its various floors, in case the moreexpensive defibrillator-monitor is more critically being deployed at anIntensive Care Unit, and so on.

AEDs, however, can also be used by people who are not in the medicalprofessions. More particularly, an AED can be used by many professionalfirst responders, such as policemen, firemen, etc. Even a person withfirst-aid and CPR/AED training can use one. And AEDs increasingly cansupply instructions to whoever is using them.

AEDs are thus particularly useful, because it is so critical to respondquickly, when a person suffers from VF. Indeed, the people who willfirst reach the VF sufferer may not be in the medical professions.

Increasing awareness has resulted in AEDs being deployed in public orsemi-public spaces, so that even a member of the public can use one, ifthey have obtained first aid and CPR/AED training on their owninitiative. This way, defibrillation can be administered soon enoughafter the onset of VF, to hopefully be effective in rescuing the person.

There are additional types of external defibrillators, which are notlisted in FIG. 2. For example, a hybrid defibrillator can have aspectsof an AED, and also of a defibrillator-monitor. A usual such aspect isadditional ECG monitoring capability. A wearable defibrillator isanother example.

FIG. 3 is a diagram showing components of an external defibrillator 300made according to embodiments. These components can be, for example, inexternal defibrillator 100 of FIG. 1. These components of FIG. 3 can beprovided in a housing 301, which is also known as casing 301.

External defibrillator 300 is intended for use by a user 380, who wouldbe the rescuer. Defibrillator 300 typically includes a defibrillationport 310, such as a socket in housing 301. Defibrillation port 310includes nodes 314, 318. Defibrillation electrodes 304, 308, which canbe similar to the electrodes of FIG. 1, can be plugged in defibrillationport 310, so as to make electrical contact with nodes 314, 318,respectively. It is also possible that electrodes can be connectedcontinuously to defibrillation port 310, etc. Either way, defibrillationport 310 can be used for guiding via electrodes to person 82 anelectrical charge that has been stored in defibrillator 300, as will beseen later in this document.

If defibrillator 300 is actually a defibrillator-monitor, as wasdescribed with reference to FIG. 2, then it will typically also have anECG port 319 in housing 301, for plugging in ECG electrode leads 309.ECG electrode leads 309 can help sense an ECG signal, e.g. a 12-leadsignal, or from a different number of leads. Moreover, adefibrillator-monitor could have additional ports (not shown), and another component 325 for the above described additional features, such aspatient signals.

Defibrillator 300 also includes a measurement circuit 320. Measurementcircuit 320 receives physiological signals from ECG port 319, and alsofrom other ports, if provided. These physiological signals are sensed,and information about them is rendered by circuit 320 as data, or othersignals, etc.

If defibrillator 300 is actually an AED, it may lack ECG port 319.Measurement circuit 320 can obtain physiological signals through nodes314, 318 instead, when defibrillation electrodes 304, 308 are attachedto person 82. In these cases, a person's ECG signal can be sensed as avoltage difference between electrodes 304, 308. Plus, impedance betweenelectrodes 304, 308 can be sensed for detecting, among other things,whether these electrodes 304, 308 have been inadvertently disconnectedfrom the person, above and beyond the present invention, or incombination with the present invention.

Defibrillator 300 also includes a processor 330. Processor 330 may beimplemented in any number of ways. Such ways include, by way of exampleand not of limitation, digital and/or analog processors such asmicroprocessors and digital-signal processors (DSPs); controllers suchas microcontrollers; software running in a machine; programmablecircuits such as Field Programmable Gate Arrays (FPGAs),Field-Programmable Analog Arrays (FPAAs), Programmable Logic Devices(PLDs), Application Specific Integrated Circuits (ASICs), anycombination of one or more of these, and so on.

Processor 330 can be considered to have a number of modules. One suchmodule can be a detection module 332, which senses outputs ofmeasurement circuit 320. Detection module 332 can include a VF detector.Thus, the person's sensed ECG can be used to determine whether theperson is experiencing VF.

Another such module in processor 330 can be an advice module 334, whicharrives at advice based on outputs of detection module 332. Advicemodule 334 can include a Shock Advisory Algorithm, implement decisionrules, and so on. The advice can be to shock, to not shock, toadminister other forms of therapy, and so on. If the advice is to shock,some external defibrillator embodiments merely report that to the user,and prompt them to do it. Other embodiments further execute the advice,by administering the shock. If the advice is to administer CPR,defibrillator 300 may further issue prompts for it, and so on.

Processor 330 can include additional modules, such as module 336, forother functions. In addition, if other component 325 is indeed provided,it may be operated in part by processor 330, etc.

Defibrillator 300 optionally further includes a memory 338, which canwork together with processor 330. Memory 338 may be implemented in anynumber of ways. Such ways include, by way of example and not oflimitation, nonvolatile memories (NVM), read-only memories (ROM), randomaccess memories (RAM), any combination of these, and so on. Memory 338,if provided, can include programs for processor 330, and so on. Theprograms can be operational for the inherent needs of processor 330, andcan also include protocols and ways that decisions can be made by advicemodule 334. In addition, memory 338 can store prompts for user 380, etc.Moreover, memory 338 can store patient data.

Defibrillator 300 may also include a power source 340. To enableportability of defibrillator 300, power source 340 typically includes abattery. Such a battery is typically implemented as a battery pack,which can be rechargeable or not. Sometimes, a combination is used, ofrechargeable and non-rechargeable battery packs. Other embodiments ofpower source 340 can include AC power override, for where AC power willbe available, and so on. In some embodiments, power source 340 iscontrolled by processor 330.

Defibrillator 300 additionally includes an energy storage module 350.Module 350 is where some electrical energy is stored, when preparing itfor sudden discharge to administer a shock. Module 350 can be chargedfrom power source 340 to the right amount of energy, as controlled byprocessor 330. In typical implementations, module 350 includes one ormore capacitors 352, and so on.

Defibrillator 300 moreover includes a discharge circuit 355. Circuit 355can be controlled to permit the energy stored in module 350 to bedischarged to nodes 314, 318, and thus also to defibrillation electrodes304, 308. Circuit 355 can include one or more switches 357. Those can bemade in a number of ways, such as by an H-bridge, and so on.

Defibrillator 300 further includes a user interface 370 for user 380.User interface 370 can be made in any number of ways. For example,interface 370 may include a screen, to display what is detected andmeasured, provide visual feedback to the rescuer for their resuscitationattempts, and so on. Interface 370 may also include a speaker, to issuevoice prompts, etc. Interface 370 may additionally include variouscontrols, such as pushbuttons, keyboards, and so on. In addition,discharge circuit 355 can be controlled by processor 330, or directly byuser 380 via user interface 370, and so on.

Defibrillator 300 can optionally include other components. For example,a communication module 390 may be provided for communicating with othermachines. Such communication can be performed wirelessly, or via wire,or by infrared communication, and so on. This way, data can becommunicated, such as patient data, incident information, therapyattempted, CPR performance, and so on.

FIG. 4 is a diagram of components of a patient electrode 410 madeaccording to embodiments, in a use context. Patient electrode 410includes a pad 404, which is configured to be attached to a skin 483 ofa patient 482. Patient electrode 410 may also include an electrode lead405 that is coupled to pad 404. A plug (not shown) may optionally beprovided, coupled to electrode lead 405, and configured to be pluggedinto a socket, such as defibrillation port 310 or ECG port 319 of FIG.3.

In some embodiments, patient electrode 410 is configured to detect anECG signal of patient 482, when attached to skin 483. In someembodiments, patient electrode 410 is configured to deliver adefibrillation pulse to patient 482 through skin 483. In someembodiments, patient electrode 410 can do both. In other words, patientelectrode 410 may be an ECG electrode, or a defibrillation electrode, orboth.

Pad 404 can be flexible, to conform to the curvature of the body ofpatient 482. Pad 404 may include a backing layer 422, and a conductivelayer 424 attached to backing layer 422. Conductive layer 424 iselectrically coupled to electrode lead 405.

Conductive layer 424 typically has adhesive, for adhering to skin 483.Even though adhesives are good and help the entire pad 404 remainattached to skin 483, sometimes there is loss of full contact 460. Lossof full contact means that pad 404 does not contact skin 483 in part, orfully. Either only a portion, or the entire pad 404, may come off skin483, neither of which is desirable. Defibrillating through a pad thathas partially come off can increase the current density through theportion of the pad that has not come off, which can harm the patient.Alternately, some of the energy might not reach the patient depending onthe electrode. And, if the pad has only partially come off, an ECG mightstill be received, thus possibly not alerting a user that the pad haspartially come off.

Patient electrode 410 may also include a contact detector 444. Contactdetector 444 may be coupled to pad 404 or electrode lead 405. Contactdetector 444 may be configured to be in one of a plurality of detectorstates. In some embodiments, contact detector 444 can change from onestate to another, when pad 404 does not contact fully skin 483. In someembodiments, the detector states are different values of an electricalproperty of the contact detector. The electrical property can beimpedance, or generation of electrical current or voltage, and so on.

In some instances, a determination is made from the current detectorstate that pad 404 does not fully contact patient skin 483. This can beaccomplished in a number of ways, which depend on the type of contactdetector 444. Some examples are described, which are not limiting. Inaddition, more than one detection techniques can be used.

In some embodiments, contact detector 444 is a temperature sensor, andthe detector state indicates a detected temperature. Normally, thedetected temperature would be that of the patient's skin 483. However,if there is loss of contact 460, the temperature sensor will sense thetemperature of the environment of skin 483, instead of that of skin 483itself. Accordingly, the determination of loss of full contact 460 canthen be made if the detected temperature changes beyond a threshold, orchanges beyond a threshold within a preset time. Adjustments should bemade for the event that the patient is being cooled, as will be obviousto a person skilled in the art in view of the present description.

In some embodiments, contact detector 444 is an optical sensor, and thedetector state indicates a detected illumination. The optical sensor canbe placed so that, when the pad is normally attached to skin 483, itprevents any light from reaching it. However, if there is loss of fullcontact 460, the optical sensor may detect illumination, which is thesame phenomenon as lifting a curtain in an otherwise dark room.Accordingly, the determination of loss of full contact 460 can then bemade if the detected illumination changes beyond a threshold.

In some embodiments, contact detector 444 is a capacitive sensor, andthe detector state indicates a detected capacitance. The capacitivesensor can be placed so that, when the pad is normally attached to skin483, the capacitive sensor detects capacitance from the mass of thepatient 482. However, if there is loss of full contact 460, thecapacitive sensor may detect a lot less capacitance, as it will not bedetecting the capacitance from the mass of the patient 482. Accordingly,the determination of loss of full contact 460 can then be made if thedetected capacitance changes beyond a threshold.

Patient electrode 410 is intended for use with an output device 470.Output device 470 is configured to emit an alert 477, when it isdetermined from the current detector state that pad 404 does not contactfully skin 483 of patient 482. The types of alert 477 are describedlater in this document.

Output device 470 may be implemented in any number of ways. It may beattached to patient electrode 410 or not. In some embodiments, outputdevice 470 is coupled to a monitor that has a module configured tomeasure a physiological parameter of patient 482. In those cases, outputdevice 470 can be used to emit another alert, if the physiologicalparameter exceeds a threshold or rescuers are to be notified.

In some embodiments, a sense signal is generated that encodes thecurrent detector state. Output device 470 can be configured to receive aversion of the sense signal, for example along path 468 in FIG. 4.

In some of those embodiments, patient electrode 410 further has a powersource (not shown). The power source can be configured to query thecontact detector about its current state, and generate the sense signalaccordingly.

The sense signal can be implemented in any number of ways. It can bewired, in which case path 468 includes at least one wire. The wire canbe implemented as a pair of sense leads, an example of which is shownlater. Alternately, the wire can be implemented via electrode lead 405,by multiplexing its function between receiving ECG and sensing thedetector. Moreover, the sense signal can be wireless, in which case path468 includes the air. A number of wireless technologies may be used,such as Bluetooth and so on.

This description also includes inventions in the field of RadioFrequency IDentification (RFID) technology, which can be applied in manyfields of remote sensing. Such inventions are described more fully laterin this document, while some of their particular applications for thepatient electrodes and systems of the invention are now described.

FIGS. 5A and 5B are diagrams of embodiments of novel use of RFIDtechnology, applied to embodiments of the novel electrodes and systemsof the invention. They are also an example where a sense signal istransmitted wirelessly according to embodiments. A patient electrodeaccording to embodiments has a pad 504, a contact detector 544 shownonly in FIG. 5B, and an RFID tag 555 coupled to contact detector 544.

In FIG. 5A, an RFID reader/interrogator 500 is configured to interrogateRFID tag 555. Reader 500 could be, for example, communication module 390of FIG. 3. Reader 500 has an antenna 501, and transmits an interrogationwave 531. Tag 555 backscatters a backscattered wave 532, withinformation from tag 555. In such embodiments, backscattered wave 532can encode the sense signal.

FIG. 5B shows more detail for pad 504. RFID tag 555 is located on thetop side of pad 504, which does not contact the patient skin. Contactdetector 544 is located on the bottom side of pad 504, which is why itis shown in dashed lines. Moreover, contact detector 544 is coupled toRFID tag 555 with jumper wires 596, which can go through pad 504, oraround an edge of it. Briefly, as contact detector 544 detects that thepad does not contact fully the skin of the patient, its electricalproperties will change, and thus operation of RFID tag 555 will beimpacted. Accordingly, reader 500 may be able to detect the loss ofcontact, by comparing backscattered wave 532 with what it expected toreceive. More detailed embodiments and explanations are provided laterin this description.

As mentioned above, in some embodiments, the output device is coupled tothe electrode. An example is now described.

FIG. 6 is a diagram of a patient electrode 610 according to embodiments.Electrode 610 has a pad 604, an electrode lead 605, and a contactdetector 644. Electrode 610 also includes an output device 670 iscoupled to pad 604. Alternately, output device 670 can be coupled toelectrode lead 605.

The output device, such as output device 670, is made according to thealert that is desired. For example, the alert can be auditory, andoutput device 670 can include a sound producing device, such as aspeaker. Or, the alert may be visual, and output device 670 can includea light producing device, such as a screen that can produce a message,an LED that can light next to appropriate writing, or picture, and soon. Or, the alert may be tactile, and output device 670 can include avibrating mechanism.

FIG. 7 shows a flowchart 700 for describing methods according toembodiments. The methods of flowchart 700 may also be practiced byembodiments described above, such as the patient electrode of FIG. 6.

According to an optional operation 710, the contact detector of thepatient electrode is queried about its current state. Optionally, asense signal is generated responsive to the current detector state.

According to another operation 720, it is determined from the currentstate whether the pad contacts fully the skin of the patient. If a sensesignal has been generated, the determination may be made from the sensesignal. If the determination of operation 720 results in “yes”,execution returns to operation 710.

If the determination of operation 720 results in “no”, then according toanother operation 730, an alert is emitted by the output device. In someembodiments, the output device receives a version of the sense signal,and emits the alert. In some embodiments, the alert signal is nullunless operation 720 results in “no”. Then the output device onlyoperates based on the sense signal being non-zero.

FIG. 8 is a diagram of a host device 800 made according to embodiments,which may use an electrode 810 according to embodiments. Host device 800may be a patient monitor, a defibrillator, a wearable defibrillator, adevice such as that of FIG. 3, and so on. Patient electrode 810 includesa pad 804, an electrode lead 805 and a contact detector 855.

Host device 800 includes an electrode port 811. Electrode port 811 isconfigured to receive electrode lead 805. As electrode port 811 can berepeated for the proper number of electrodes, it will become similar toport 310 or port 319 of FIG. 3. Optionally, host device 800 could alsohave a module configured to measure an ECG of the patient throughelectrode port 811, such as module 320 of FIG. 3.

Host device 800 also includes a sense port 812. Sense port 812 isconfigured to receive a sense signal from contact detector 855.

In the embodiment of FIG. 8, electrode 810 includes sense leads 868, andsense port 812 is a physical port for receiving sense leads 868. Thesense signal is thus transferred from electrode 810 via sense leads 868to host device 800. Equivalently, the sense signal could be transferredwirelessly as seen in FIG. 5A, in which case sense port 812 is awireless receiver such as reader 500 or communication module 390 of FIG.3.

Host device 800 further includes an output device 870. Output device 870is configured to emit an alert, if it is detected from the sense signalthat pad 804 does not contact fully the skin of the patient.

Optionally, host device 800 may also include other components. Forexample, it may include a processor 830. Processor 830 may be configuredto detect from the sense signal whether electrode 810 does not contactfully the skin of the patient.

Host device 800 may further include a memory 838, which can worktogether with processor 830. Memory 838 may be implemented in any numberof ways. Such ways include, by way of example and not of limitation,volatile memories, nonvolatile memories (NVM), read-only memories (ROM),random access memories (RAM), magnetic disk storage media, opticalstorage media, smart cards, flash memory devices, any combination ofthese, and so on. Memory 838 is thus a non-transitory storage medium.Memory 838, if provided, can include programs for processor 830 toexecute. Executing is performed by physical manipulations of physicalquantities, and may result in the functions, processes and/or methods tobe performed, and/or the processor to cause other devices or componentsor blocks to perform such functions, processes, actions and/or methods.The programs can include sets of instructions. The programs can beoperational for the inherent needs of processor 830.

In addition, memory 838 can store prompts for a user. Moreover, memory838 can store data. The data can include patient data, system data andenvironmental data. The data can be stored in memory 838 before it istransmitted out of host device 800.

Plus, host device 800 may further be configured to make an entry in thememory, if it is detected that the electrode does not contact fully theskin of the patient. The entry can be of the date, time, other availabledata including patient data, and efforts to emit the alert.

Moreover, host device 800 may include another module 825. Other module825 can be configured to measure a physiological parameter of thepatient, which can be other than the patient's ECG. In some embodiments,the local parameter is a trend that can be detected in a monitoredphysiological parameter of the patient. A trend can be detected bycomparing values of parameters at different times.

Additionally, host device 800 may include a defibrillator 888.Defibrillator 888 can be configured to transmit an electricaldefibrillation pulse through electrode port 811, in the event thatelectrode 810 is a defibrillation electrode.

As described above, the alert can be auditory, visual or tactile. Insome embodiments, the alert identifies the electrode that is coming offthe skin, thus distinguishing it from another electrode. The alert couldinclude a picture of the electrode in question. The picture could alsobe in a context, such as indicating the location of the electrode.

Host device 800 may also emit the alert electronically to a remote caregiver, as a transmitted message. The message may be transmitted over acommunication network wirelessly or not.

In some embodiments, host device 800 is part of a wearabledefibrillation system. Embodiments are now described in more detail,also with reference to FIG. 9.

A wearable defibrillator system made according to embodiments has anumber of components. One of these components is a support structure,which is configured to be worn by the patient. The support structure canbe any structure suitable for wearing, such as a harness, a vest, one ormore belts, another garment, and so on. The support structure can beimplemented in a single component, or multiple components. For example,a support structure may have a top component resting on the shoulders,for ensuring that the defibrillation electrodes will be in the rightplace for defibrillating, and a bottom component resting on the hips,for carrying the bulk of the weight of the defibrillator. A singlecomponent embodiment could be with a belt around at least the torso.Other embodiments could use an adhesive structure or another way forattaching to the person, without encircling any part of the body. Therecan be other examples.

FIG. 9 is a diagram of components of a wearable defibrillator systemmade according to embodiments, as it might be worn by a patient 982.Patient 982 may also be referred to as person 982, and/or wearer 982since he or she wears components of the wearable defibrillator system.

In FIG. 9, a generic support structure 950 is shown relative to the bodyof person 982, and thus also relative to his or her heart 985. Structure950 could be a harness, a vest, one or more belts, a garment, as per theabove; it could be implemented in a single component, or multiplecomponents, and so on. Structure 950 is wearable by person 982, but themanner of wearing it is not depicted, as structure 950 is depicted onlygenerically in FIG. 9.

A wearable defibrillator system is configured to defibrillate thepatient, by delivering electrical charge to the patient's body in theform of an electric shock or one or more pulses. FIG. 9 shows a sampleexternal defibrillator 900, and sample defibrillation electrode pads904, 908, which are coupled to external defibrillator 900 via electrodeleads 905. Defibrillator 900 can be made as device 300 of FIG. 3, or inother ways. Defibrillator 900 is coupled to support structure 950. Assuch, all components of defibrillator 900 can be therefore coupled tosupport structure 950. When defibrillation electrode pads 104, 108 makegood electrical contact with the body of person 982, defibrillator 900can administer a brief, strong electric pulse 911 through the body,similar to pulse 111 of FIG. 1.

A wearable defibrillator system according to embodiments includes anoutput device 970. In some embodiments, output device 970 is coupled tosupport structure 950. In some of these embodiments, output device 970is coupled such that it is positioned near the patient's shoulder. Thisway, an alert that is intended for wearer 982 can be heard morereliably, if it is audible.

It should be remembered that a wearable defibrillator system accordingto embodiments may include electrodes that can have another outputdevice on the pad, or the output device only on the pad. This way atactile alert will be perceived at the location of the worn electrode.

The above-mentioned devices and/or systems perform functions, processesand/or methods, as described in this document. The functions, processesand/or methods may be implemented by one or more devices that includelogic circuitry. The logic circuitry may include a processor that may beprogrammable for a general purpose, or dedicated, such as processor 830.

Moreover, methods and algorithms are described below. These methods andalgorithms are not necessarily inherently associated with any particularlogic device or other apparatus. Rather, they are advantageouslyimplemented by programs for use by a computing machine, such as ageneral-purpose computer, a special purpose computer, a microprocessor,etc.

Often, for the sake of convenience only, it is preferred to implementand describe a program as various interconnected distinct softwaremodules or features, individually and collectively also known assoftware. This is not necessary, however, and there may be cases wheremodules are equivalently aggregated into a single program, even withunclear boundaries. In some instances, software is combined withhardware, in a mix called firmware.

This detailed description includes flowcharts, display images,algorithms, and symbolic representations of program operations within atleast one computer readable medium. An economy is achieved in that asingle set of flowcharts is used to describe both programs, and alsomethods. So, while flowcharts described methods in terms of boxes, theyalso concurrently describe programs.

A method is now described.

FIG. 10 shows a flowchart 1000 for describing methods according toembodiments. The methods of flowchart 1000 may also be practiced byembodiments described above, such as host device 800.

According to an operation 1010, an electrode lead is received throughthe electrode port. The electrode lead is of an electrode having a padfor contacting a patient's skin, and a contact detector.

According to another operation 1020, a sense signal is received throughthe sense port. The sense signal is received from the contact detector,either via sense leads or wirelessly.

According to another operation 1030, it is determined whether the padcontacts fully the skin of the patient. The determination may be fromthe received sense signal, which informs of the state of the contactdetector. In some embodiments, the sense signal is null unless operation1030 results in “no”. In some embodiments, the sense signal is nonzero.Depending on the design, there can be an affirmative operation ofdetermining from the sense signal whether the electrode does not contactfully the skin of the patient. If the determination of operation 1030results in “yes”, execution returns to operation 1010.

If the determination of operation 1030 results in “no”, then accordingto another operation 1040, an alert is emitted by the output device. Insome embodiments, the alert signal is null unless operation 1030 resultsin “no”. Then the output device only operates based on the sense signalbeing non-zero. The alert may be emitted as mentioned above.

According to another, optional operation 1050, an entry is made in amemory. The entry can be made if it is detected that the electrode doesnot contact fully the skin of the patient.

There can be further other optional operations. For example, an ECG ofthe patient can be measured through the electrode port. Or aphysiological parameter of the patient, other than the patient's ECG,can be measured. Or, an electrical defibrillation pulse can betransmitted through the electrode port.

Moreover, the output device may be used also for other notifications.For example, another condition of the patient may be detected, such asfrom measuring their physiological parameters. The condition may be thata parameter is trending in a way that causes concern, and so on. Whenthe other condition is detected, the output device may emit an alert.

The invention also includes methods for processor 830. Processor 830receives inputs and causes devices, modules and components to executefunctions. Some of the resulting methods are those of FIG. 10.

In some embodiments, a processor may decode a sense signal. The sensesignal may have been received through the sense port. The sense signalmay be from a contact detector of an electrode that has a pad forcontacting a patient's skin. Then it may be determined from the sensesignal whether the pad does not contact fully the skin of the patientand, if so, the output device can be caused to emit an alert. The alertscan be as above.

RFID-Based Sensing

FIG. 11 is a diagram illustrating RFID-based wireless sensing of achanged condition, according to embodiments. It will be appreciated thatthe sensing can be in any number of frequencies, such as 13.56 MHz, 900MHz, 2.4 GHz and so on. Moreover, where two RFID tags are shown, it ispreferred and advantageous that they work in the same frequency, butthat is not necessary.

A changed condition 1172 is shown in FIG. 11 at a location 1171. Thecondition that could change is illumination, temperature, availablemass, capacitance, sound, pressure, humidity, and so on, and the desireis to have a system that detects it without the need for inspection, forexample whether a basement leaks water, electrodes losing full contact,etc. A person skilled in the art will find many more uses.

Embodiments include an RFID-based sensor 1110. Sensor 1110 includes abase 1173 that is optional and highly preferred. One or all the othercomponents of sensor 1110 can be coupled to base 1173. Base 1173 can bemade in any way suitable for the described functions such as, forexample, from plastic that is hard or flexible.

If the change of condition needs to be detected at a specific locationsuch as location 1172, then base 1173 could be configured to be placedat that location. For example, base 1173 may further have provisions forits attachment, such as a clear flap suitable for gluing or nailing to aplace of interest. It is also recommended that base 1173 have a cleararea to accommodate writing, for better identification of the sensors attheir locations.

Sensor 1110 also includes a sensing RFID tag 1155. Sensing RFID tag 1155may be coupled to base 1173, if provided. The word “sensing” in the nameof sensing RFID tag 1155 is only for distinguishing from the other RFIDtag, if provided. Advantageously, sensing RFID tag 1155 can be procuredfrom commercially available RFID tags.

Sensor 1110 additionally includes a detector 1144. Detector 1144 has anelectrical property that may change responsive to a change in thecondition, which is why an arrow is shown from changed condition 1172 todetector 1144. The detector can be of the technology applicable for thecondition to be detected. As such, the detector can be a light detector,a temperature sensor, a capacitance sensor, a sound detector, a pressuresensor such as piezoelectric technology, a humidity detector, and so on.Depending on the operation of the detector, the electrical property thatchanges when the condition changes can be a generated voltage, agenerated current, a changed impedance, and so on.

In addition, detector 1144 is electrically coupled to sensing RFID tag1155. Coupling can be by manufacturing detector 1144 suitably close tothe RFID tag. Alternately, detector 1144 can be electrically coupled viajumper wires 1196. If used, jumper wires 1196 are preferably kept short.Changed condition 1172 will generate a change in the electrical propertyof detector 1144, which in turn will impact an operation of sensing RFIDtag 1155. The change in operation can be detected by an interrogatingRFID reader, which will thus know about the changed condition 1172.

Sensor 1110 optionally also includes a reference RFID tag 1156.Reference RFID tag 1156 may be coupled to base 1173, if provided. Again,reference RFID tag 1156 can be procured from commercially available RFIDtags. If reference RFID tag 1156 will be used for dynamically writing toit periodic information such as received signal strength, then it shouldbe the type that can be written.

Reference RFID tag 1156 is not electrically coupled to detector 1144 asis sensing RFID tag 1155. This means that reference RFID tag 1156 iscoupled to detector differently than sensing RFID tag 1155, or not atall. As such, while the changed condition will impact the operation ofsensing RFID tag 1155, it will not impact that of reference RFID tag1156.

In fact, it should be considered that in location 1171, if there is achanged condition 1172, the operation of both tags may be affected. Thatis why, in some embodiments, sensor 1110 also includes a shield that isconfigured to shield reference RFID tag 1156 differently than sensingRFID tag 1155, so that the latter will not be impacted by changedcondition 1172. Shielding differently means that sensing RFID tag 1155may be shielded in part, or not at all, by the shield.

More can be done by exploiting the Electronic Product Codes (EPCs) thatcan be stored in the memories of RFID tags 1155, 1156. For example,sensing RFID tag 1155 can have a first memory that stores a first EPC(“EPC1”), and reference RFID tag 1156 can have a second memory thatstores a second EPC (“EPC2”). EPC2 can be related to EPC1, so that anRFID reader will know the relationship of the two RFID tags, and it willbe easier to select them for interrogation while quieting any other tagsin location 1171. In fact, the first EPC could include a string incommon with the second EPC.

Embodiments include an RFID reader 1100, which can be configured tosense the impacted operation of sensing RFID tag 1155. RFID reader 1100may have an antenna 1101, a processor 1130, and a memory 1138 that couldstore reader software applications (“apps”) 1139 according toembodiments. Antenna 1101 can transmit and receive waves at the desiredfrequency for the RFID application. In some embodiments, a differentantenna transmits, while antenna 1101 receives. A Received SignalStrength Indicator (RSSI) module may also be provided with reader 1100,which is configured to measure a strength of the backscattered signal.

RFID reader 1100 may transmit an interrogation wave 1131 towardslocation 1171, where sensor 1110 is at. Antenna 1101 may receive abackscattered wave 1132 in response to the transmitted wave.Backscattered wave 1132 will include response 1141 from sensing RFID tag1155, and response 1142 from reference RFID tag 1156, if provided. Ascan be seen from FIG. 11, response 1141 can be code EPC1, and response1142 can be code EPC2. Moreover, if reader 1100 follows a protocol thatsingulates the RFID tags, it will be able to discern code EPC1 from codeEPC2. However, response 1141 may be received at a different strength,also known as signal strength, if changed condition 1172 has causeddetector 1144 to impact the operation of sensing RFID tag 1155. And, aswill be seen in embodiments, response 1141 might be too weak to bereceived, or it might not be received at all, and that is why it isdrawn as a “whisper”.

Accordingly, from the strength of backscattered wave 1132, processor1130 may be able to determine that condition 1172 has changed. Processor1130 may be further configured to transmit an alert to an operator or amonitoring service, if condition 1172 has changed.

The determination can be made in a number of ways. In one embodiment,the determination can be made by comparing the strength of response 1141to a strength of a previously received backscatter from the location. Avalue of that strength may have been stored in memory 1138 for futurecomparison. If the strength of the presently backscattered wave hasbecome less, then the condition may be changing.

In an additional embodiment, the determination is made if the strengthof the backscattered wave is lower than a threshold. The threshold canbe set appropriately. This type of embodiment also takes care of thepossibility that backscattered wave 1132 reaching antenna 1101 is tooweak to be measured, or that response 1141 is not generated at all.

In another embodiment, the backscattered wave includes a stored value ofa previously measured signal strength from the location. In other words,once that signal strength was measured previously, its value stored backin the memory of sensing RFID tag 1155, for future comparison. Thedetermination can then be made by comparing the strength of thepresently backscattered wave to the stored value. Also, memory 1138 canbe configured to store the value of present response 1141, for futurecomparison.

In one more embodiment, the determination is made by effectivelycomparing the signal strength of response 1141, which is presumed to bebackscattered by sensing RFID tag 1155, to that of response 1142, whichis presumed to be backscattered by reference tag 1156. In an idealsituation, when there is no changed condition, the signal strengths ofresponses 1141 and 1142 could be identical. Due to jumper wires 1196,however, they might not be. Still, their ratio can provide goodguidance—if it deteriorates in the future, that could mean there ischanged condition 1172. So, the determination can be made by comparing adetected ratio of the strength of the first response to that of thesecond response, against that of a previously detected ratio. Plus,performance values of sensing RFID tag 1155 can be stored in the memoryof the reference tag 1156 that is less prone to loss due to changedcondition 1172. The strength of this technique is that changes in otherconditions are not automatically misinterpreted as changed condition1172, because the backscatter signal strength of the reference tag 1156will also be affected. An example of another such condition is if reader1100 subsequently transmits at lesser power.

As has been mentioned, sensor 1110 is specially made such that thechange in the electrical property of detector 1144 will impact theperformance of sensing RFID tag 1155. Moreover, it is very economical toachieve this by procuring a commercially available RFID tag as sensingRFID tag 1155, and generally electrically coupling it to detector 1144via jumper wires 1196. Particular examples of such coupling are nowdescribed with reference to FIGS. 12 and 13.

FIG. 12 is a diagram illustrating electrical connections for anRFID-based sensor according to embodiments. Sensing RFID tag 1255 has asubstrate 1291 and a sensing antenna 1292 on substrate 1291. The term“sensing” in the name of sensing antenna 1292 is only to distinguishfrom the antenna of any other RFID tag, if provided. The sensing antennacan be any shape. The specific shape of sensing antenna 1292 in theexample of FIG. 12 is from U.S. Design Pat. D543,976S to Impinj for the900 MHz range, and chosen here so that the simplicity of its patternwould not unnecessarily confuse the description, but many other antennadesigns may work just as well, or even better.

Sensing RFID tag 1255 also has a tag chip 1293 on substrate 1291. Tagchip 1293 is a rectangle that is much smaller than sensing antenna 1292,and has conductive pads at its corners. Antenna 1292, as well as manyother antennas, terminates in four edges that are contacted by theconductive pads of tag chip 1293.

A detector 1244 is electrically coupled to sensing antenna 1292, byjumper wires 1296 that are electrically connected at nodes 1297.Coupling can be by soldering. If antenna 1292 is covered by a plasticcover, that cover may have to be removed first at the location of nodes1297.

The connections of FIG. 12 can be used so that the performance ofsensing RFID tag 1255 will be impacted mainly by detuning the sensingantenna. Indeed, when the electrical property of detector 1244 changesbecause of the changed condition, the impact on sensing antenna 1292will be felt from nodes 1297, which are “in the middle” of sensingantenna 1292, and “far” from where it contacts tag chip 1293. Theantenna properties will likely change, and thus its reflectivity willchange.

If a commercially available RFID tag 1255 has been used that was alreadytuned to optimum reflectivity, then the changing property of detector1244 will detune it and diminish the reflectivity. That is why response1141 may be weak.

Not all detectors work the same way. In general, a meshing circuit 1245can be coupled between detector 1244 and sensing antenna 1292. In theexample of FIG. 12, meshing circuit 1245 is coupled in parallel.

Meshing circuit 1245 can be designed so that the particular changingproperty of detector 1244 becomes an important effect that impacts theoperation of tag chip 1255, and in this case its reflectivity. Forexample, meshing circuit 1245 could have a resistor, a capacitor, both,etc. If detector 1244 changes impedance due to the changed condition,then meshing circuit 1245 can provide impedance of a suitable value thatis added in parallel.

The connections of FIG. 12 can be also used to disrupt the tag chipoperation. For example, if detector 1244 generates current due to thechanged condition, then meshing circuit 1245 can be a high resistanceresistor that creates a DC voltage, some of which can be applied to tagchip 1293.

FIG. 13 is a diagram illustrating electrical connections for anRFID-based sensor according to embodiments. Sensing RFID tag 1355 has asubstrate 1391 and a sensing antenna 1392 on substrate 1391. Sensingantenna 1392 is the same as antenna 1292, to further illustrate thedifference. Sensing RFID tag 1355 also has a tag chip 1393 on substrate1391.

A detector 1344 is electrically coupled to sensing antenna 1392, byjumper wires 1396 that are electrically connected at nodes 1397.Coupling can be by soldering.

A meshing circuit 1345 can be coupled between detector 1344 and sensingantenna 1392. In the example of FIG. 13, meshing circuit 1345 is coupledin series.

The connections of FIG. 13 are intended so that the performance ofsensing RFID tag 1355 will be impacted mainly by disrupting theoperation of tag chip 1393. Indeed, when the electrical property ofdetector 1344 changes because of the changed condition, the impact willbe felt from nodes 1397, which are near tag chip 1393. For example, ifdetector 1344 generates current due to the changed condition, thenmeshing circuit 1345 can be a high resistance resistor that creates a DCvoltage, some of which can be applied to tag chip 1393. Depending on thedesign of tag chip 1393, the DC voltage may impact the operation of thedemodulator and/or the modulator of tag chip 1393, perhaps preventing itfrom sensing properly the reader signal, or responding properly. Thiswill be achieved more easily if an antenna design is chosen, and nodesare chosen that are not shorted to each other by the antenna itself.

An advantage is that, while it was intended to impact tag chip 1393,this was accomplished without having to solder to its pads, but bychoosing nodes 1397 near it. Reasons to use a commercially availableRFID tag are both that it is cheap, and that the low cost alreadyincorporates the made connection between antenna 1392 and tag chip 1393that requires high precision to make.

Other options include making custom antenna designs for such chips, anddesigning the detector in the tag chip, especially if the latter can beimplemented in CMOS.

FIG. 14 shows a flowchart 1400 for describing methods according toembodiments. The methods of flowchart 1400 may also be practiced byembodiments described above, such as by reader 1100 or one of itscomponents, for example by reader software.

According to an optional operation 1410, an interrogation wave istransmitted towards the location of interest. Preferably, a sensor suchas sensor 1110 has been placed there, and which has one or more RFIDtags.

According to another operation 1420, a backscattered wave is received.The backscattered wave may be received in response to the interrogationwave. The backscattered wave may have encoded information thatidentifies the sensor that is responding this way.

According to another, optional operation 1430, the strength of thereceived backscattered wave is detected. The detected strength may alsobe recorded, both locally in the reader and also in an RFID tag on theresponding sensor.

According to another operation 1440, it is determined whether acondition has changed at the location. The determination can be madefrom the strength of the backscattered wave, and also as describedabove. If not, then execution may return to operation 1410.

If yes, then according to another operation 1450, an alert istransmitted. The alert can be transmitted by proper messaging to adifferent module in the host or a different device.

In the methods described above, each operation can be performed as anaffirmative step of doing, or causing to happen, what is written thatcan take place. Such doing or causing to happen can be by the wholesystem or device, or just one or more components of it. In addition, theorder of operations is not constrained to what is shown, and differentorders may be possible according to different embodiments. Moreover, incertain embodiments, new operations may be added, or individualoperations may be modified or deleted. The added operations can be, forexample, from what is mentioned while primarily describing a differentsystem, device or method.

This description includes one or more examples, but that does not limithow the invention may be practiced. Indeed, examples or embodiments ofthe invention may be practiced according to what is described, or yetdifferently, and also in conjunction with other present or futuretechnologies.

A person skilled in the art will be able to practice the presentinvention in view of this description, which is to be taken as a whole.Details have been included to provide a thorough understanding. In otherinstances, well-known aspects have not been described, in order to notobscure unnecessarily the present invention.

Other embodiments include combinations and sub-combinations of featuresdescribed herein, including for example, embodiments that are equivalentto: providing or applying a feature in a different order than in adescribed embodiment; extracting an individual feature from oneembodiment and inserting such feature into another embodiment; removingone or more features from an embodiment; or both removing a feature froman embodiment and adding a feature extracted from another embodiment,while providing the advantages of the features incorporated in suchcombinations and sub-combinations.

The following claims define certain combinations and subcombinations ofelements, features and steps or operations, which are regarded as noveland non-obvious. Additional claims for other such combinations andsubcombinations may be presented in this or a related document.

1-58. (canceled)
 59. A Radio Frequency Identification (RFID)-basedsensor configured to sense a change in a condition, comprising: asensing RFID tag that has a first memory, the first memory configured tostore a first Electronic Product Code (EPC); a detector having anelectrical property that changes responsive to a change in thecondition, the detector being electrically coupled to the sensing RFIDtag so as to impact an operation of the sensing RFID tag responsive tothe change in the condition; a reference RFID tag that is notelectrically coupled to the detector as is the sensing RFID tag, thereference RFID tag having a second memory that is configured to store asecond EPC; and a base, and in which the sensing RFID tag, the referenceRFID tag and the detector are coupled to the base.
 60. The sensor ofclaim 59, in which the detector is one of a light detector, atemperature sensor, a capacitance sensor, a sound detector, a pressuresensor and a humidity detector.
 61. The sensor of claim 59, in which theelectrical property includes at least one of a generated voltage, agenerated current, and a changed impedance.
 62. The sensor of claim 59,in which the sensing RFID tag is electrically coupled to the detectorvia jumper wires.
 63. The sensor of claim 59, in which the sensing RFIDtag has a sensing antenna, and the detector is electrically coupled tothe sensing antenna via jumper wires.
 64. A Radio FrequencyIdentification (RFID)-based sensor configured to sense a change in acondition, comprising: a sensing RFID tag that has a sensing antenna; adetector having an electrical property that changes responsive to achange in the condition, the detector being electrically coupled to thesensing antenna of the sensing RFID tag so as to impact an operation ofthe sensing RFID tag responsive to the change in the condition; ameshing circuit coupled between the detector and the sensing antenna; areference RFID tag that is not electrically coupled to the detector asis the sensing RFID tag; and a base, and in which the sensing RFID tag,the reference RFID tag and the detector are coupled to the base.
 65. Thesensor of claim 64, in which the detector is one of a light detector, atemperature sensor, a capacitance sensor, a sound detector, a pressuresensor and a humidity detector.
 66. The sensor of claim 64, in which theelectrical property includes at least one of a generated voltage, agenerated current, and a changed impedance.
 67. The sensor of claim 64,in which the meshing circuit is coupled between the detector and thesensing antenna in parallel.
 68. The sensor of claim 64, in which themeshing circuit is coupled between the detector and the sensing antennain series.
 69. A Radio Frequency Identification (RFID)-based sensorconfigured to sense a change in a condition, comprising: a sensing RFIDtag that has a first memory, the first memory configured to store afirst Electronic Product Code (EPC); a detector having an electricalproperty that changes responsive to a change in the condition, thedetector being electrically coupled to the sensing RFID tag so as toimpact an operation of the sensing RFID tag responsive to the change inthe condition; a reference RFID tag that is not electrically coupled tothe detector as is the sensing RFID tag, the reference RFID tag having asecond memory that is configured to store a second EPC; and a shieldconfigured to shield the reference RFID tag differently than the sensingRFID tag.
 70. The sensor of claim 69, further comprising: a base, and inwhich the sensing RFID tag and the detector are coupled to the base. 71.The sensor of claim 69, in which the detector is one of a lightdetector, a temperature sensor, a capacitance sensor, a sound detector,a pressure sensor and a humidity detector.
 72. The sensor of claim 69,in which the electrical property includes at least one of a generatedvoltage, a generated current, and a changed impedance.
 73. A RadioFrequency Identification (RFID)-based sensor configured to sense achange in a condition, comprising: a base; a sensing RFID tag coupled tothe base and having a sensing antenna; a detector coupled to the base,the detector having an electrical property that changes responsive to achange in the condition, the detector being electrically coupled to thesensing antenna of the sensing RFID tag so as to impact an operation ofthe sensing RFID tag responsive to the change in the condition; ameshing circuit coupled between the detector and the sensing antenna; areference RFID tag that is not electrically coupled to the detector asis the sensing RFID tag; and a shield configured to shield the referenceRFID tag differently than the sensing RFID tag.
 74. The sensor of claim73, in which the detector is one of a light detector, a temperaturesensor, a capacitance sensor, a sound detector, a pressure sensor and ahumidity detector.
 75. The sensor of claim 73, in which the electricalproperty includes at least one of a generated voltage, a generatedcurrent, and a changed impedance.
 76. The sensor of claim 73, in whichthe meshing circuit is coupled between the detector and the sensingantenna in parallel.
 77. The sensor of claim 73, in which the meshingcircuit is coupled between the detector and the sensing antenna inseries.